et al ; just as a point of clarification, there should be no metal at all in the Burn Tunnel, there are many was to make a RMH, but because we want Reflective materials only,that
absorb very little of the heat, and instead re-radiate it back into the Combustion zone to rapidly bring your rocket up to its freakishly high operating temperatures, metal would
be a poor choice at that location.
The only reason to have any metal surface to be found on the Heat Riser, is as a sacrificial form, soon to be burned away, the thinest metal possible would barely be little
enough for the same reasons listed for the Burn Tunnel, Temperatures in the Heat Riser should be 1600 dF and higher ! For the Craft ! Big AL
Success has a Thousand Fathers , Failure is an Orphan
We have found an emissivity coating for the inside of our cast refractory burn tunnels. Unfortunately, we have not tested it side by side with an uncoated version to see what the performance difference is. Theoretically, it should make the burn tunnels last longer. It is not made for metals, just refractory materials.
I can tell you it has be applied keeping the solution well mixed, which is difficult. It is also extremely expensive. It is available through your local refractory supplies dealer.